The present invention relates to a high-efficiency power generating method.
In recent years, fractional distillation of crude oil or heavy oil in an electric power generating plant has been studied. A light oil fraction (low boiling point component) obtained by fractional distillation is sent to a gas turbine, and is burned therein, by which electric power is generated. High-temperature combustion exhaust gas obtained by the gas turbine is sent to a boiler in place of air, a heavy oil fraction (high boiling point component) is burned in the boiler, and a steam turbine is rotated by high-temperature, high-pressure steam produced in the boiler, by which electric power is generated. That is to say, a method is provided in which electric power is generated while what is called repowering, in which exhaust gas of a gas turbine is charged into a boiler and is re-burned, is performed.
As means for distilling crude oil or heavy oil, atmospheric distillation has generally been used, in which crude oil or heavy oil is distilled by being heated to about 360xc2x0 C. As means for heating, a heating furnace has been used to obtain the above-described heating temperature. The heating furnace generally burns fuel to obtain thermal energy, and heats stock oil by radiation heat generated during burning and by convection of combustion gas.
The use of such a heating furnace allows the crude oil or heavy oil to be heated easily to a high temperature. When such a heating furnace is used, however, there arise problems such that heat loss of exhaust gas is created, the thermal efficiency is low, and treatment of SOx and NOx in exhaust gas is needed.
The present invention has been made in view of the above situation, and accordingly an object thereof is to provide a high-efficiency power generating method in which a heating furnace is disused, so that a problem of heat loss of exhaust gas is solved, and no load for treatment of SOx and NOx in exhaust gas is added to a power generating system, whereby the power generating efficiency of an exhaust gas re-combustion system is further enhanced as a whole.
Accordingly, the present invention provides a high-efficiency power generating method to generate electric power by an exhaust gas re-combustion system using at least a gas turbine, a boiler, and a steam turbine, comprising the steps of heating crude oil or heavy oil with steam obtained from the boiler; distilling the crude oil or heavy oil under reduced pressure; and generating electric power by using an obtained light oil fraction as a gas turbine fuel and by using a heavy oil fraction as a boiler fuel.
In accordance with the present invention, the crude oil or heavy oil can be heated easily by providing means for effecting heat exchange between the crude oil or heavy oil and the light oil fraction and/or heavy oil fraction obtained in a distillation column.
Also, in accordance with the present invention, a steam ejector can be used as means for reducing the pressure for vacuum distillation.
The present invention provides a high-efficiency power generating method in which a heating furnace is disused, so that a problem of heat loss of exhaust gas is solved, and no load for treatment of SOx and NOx in exhaust gas is added to a power generating system, whereby the power generating efficiency of an exhaust gas re-combustion system is further enhanced as a whole.